JP4422504B2 - Switching power supply device and control method thereof - Google Patents

Description

  The present invention relates to a switching power supply apparatus that supplies a DC stabilized voltage to industrial and consumer electronic devices and a control method therefor. In particular, the present invention relates to an improvement in stability of a switching power supply device configured by a plurality of switching power supply circuits.

In recent years, as electronic devices have become cheaper, smaller, higher performance, and more energy efficient, the power supply devices used in such electronic devices are also low cost, small size, stable output, and highly efficient switching power supplies. Is strongly demanded. In particular, with a power supply for supplying power to a semiconductor device, a demand for a power supply device capable of supplying a large current with a lower voltage and higher stability is increasing as the semiconductor is highly integrated. In a switching power supply circuit in a switching power supply device, a rectangular wave AC voltage is formed by a switching element that repeatedly turns on and off, and after changing to a desired AC voltage using a high-frequency transformer, it is converted to a DC voltage by a rectifier circuit and a smoothing circuit. is doing. The transformer used in this switching power supply device has a structure in which a primary winding and a secondary winding of a transformer are wound around a magnetic material a plurality of times, and a voltage applied to the winding and an induced voltage adjust the number of turns. It is the structure changed by doing. Generally, in a switching power supply circuit, a voltage is roughly changed by a transformer, and fine adjustment of the voltage is performed by PWM control of an on / off ratio of the switching element. The number of turns of the primary winding and the secondary winding of the transformer is mainly determined by the applied voltage, and the required number of turns increases as the voltage increases. When the number of turns of the transformer increases, the volume of the portion necessary for insulating the windings increases, resulting in a problem that the outer shape of the transformer becomes large.

A voltage substantially proportional to the input voltage is applied to the switching element in the switching power supply circuit, and a high voltage is applied when the input voltage is high. As the switching element, a semiconductor element is mainly used. In the case of a semiconductor element having a high voltage applied at the time of turning off, the resistance and voltage drop at the time of turning on are generally large. As a result, the loss in the semiconductor element increases, and the heat dissipating means for dissipating the heat accompanying the loss increases, making it difficult to achieve downsizing of the device. In order to solve this problem, a configuration is considered in which the input sides of a plurality of switching power supply circuits are connected in series to reduce the voltage applied to each switching element.

As a conventional input-side serial connection method for a plurality of switching power supply circuits in a switching power supply device, the one described in Japanese Patent Application Laid-Open No. 62-138061 is known.
FIG. 4 is a circuit diagram showing a configuration example of a conventional switching power supply circuit in which a plurality of switching power supply circuits are connected in series on the input side. In FIG. 4, an input DC voltage from an input DC power supply 201 is supplied to input terminals 202a and 202b, and a series circuit of a plurality of capacitors 203, 204, 205, and 206 is connected to the input terminals 202a and 202b. The input DC voltage applied to the input terminals 202a and 202b is divided by the capacitors 203, 204, 205, and 206. In the following description, each of a plurality of capacitors 203, 204, 205, 206 connected to the input terminals 202a, 202b is replaced with a first capacitor 203, a second capacitor 204, a third capacitor 205, and a fourth capacitor 206. Called. A series circuit of the first switching element 207 and the second switching element 208 is connected to both ends of the series circuit of the first capacitor 203 and the second capacitor 204, and the third capacitor 205 and the fourth capacitor 206 are connected to each other. A series circuit of a third switching element 209 and a fourth switching element 210 is connected to both ends of the series circuit.

The first transformer 211 has a primary winding 211a, a first secondary winding 211b, and a second secondary winding 211c. One end of the primary winding 211a is connected to the connection point of the first capacitor 203 and the second capacitor 204, and the other end of the primary winding 211a is the first switching element 207 and the second switching element 208. Connected to the connection point. The first secondary winding 211b and the second secondary winding 211c are connected in series.
The second transformer 212 includes a primary winding 212a, a first secondary winding 212b, and a second secondary winding 212c. One end of the primary winding 212 a is connected to the connection point of the third capacitor 205 and the fourth capacitor 206, and the other end of the primary winding 212 a is the third switching element 209 and the fourth switching element 210. Connected to the connection point. The first secondary winding 212b and the second secondary winding 212c are connected in series.

The anode of the first rectifier diode 213 is connected to the first secondary winding 211b of the first transformer 211, and the anode of the second rectifier diode 214 is connected to the second secondary winding 211c. Has been. The cathodes of the first rectifier diode 213 and the second rectifier diode 214 are connected to each other. In this way, the first rectifier diode 213 and the second rectifier diode 214 are connected to the first transformer 211, and the voltage generated in the first secondary winding 211b and the second secondary winding 211c. Rectified.
As shown in FIG. 4, one end of the series circuit of the first choke coil 215 and the smoothing capacitor 216 is connected to a connection point between the first secondary winding 211b and the second secondary winding 211c. The other end of the series circuit is connected to a connection point (cathode) between the first rectifier diode 213 and the second rectifier diode 214.

The anode of the third rectifier diode 217 is connected to the first secondary winding 212b of the second transformer 212, and the anode of the fourth rectifier diode 218 is connected to the second secondary winding 212c. Has been. The cathodes of the third rectifier diode 217 and the fourth rectifier diode 218 are connected to each other. In this way, the third rectifier diode 217 and the fourth rectifier diode 218 are connected to the second transformer 212, and the voltages generated in the first secondary winding 212b and the second secondary winding 212c. Rectified.
One end of the second choke coil 219 is connected to the connection point (cathode) of the third rectifier diode 217 and the fourth rectifier diode 218, and the other end is connected to one end of the smoothing capacitor 216. Both ends of the smoothing capacitor 216 are connected to the output terminals 220a and 220b, and power is consumed by the load 221 connected to the output terminals 220a and 220b.

As shown in FIG. 4, the voltage generated at the positive output terminal 220 a is input to one of the error amplifiers 223, and the reference voltage from the reference power supply 222 is input to the other of the error amplifiers 223. The error amplifier 223 compares the output voltage of the output terminals 220a and 200b with the reference voltage of the reference power supply 222, and amplifies the error.
The triangular wave generating circuit 224 forms a reference triangular wave that serves as a reference for forming a PWM signal supplied from the first switching element 207 to each of the fourth switching elements 210. The formed reference triangular wave is input to one side of the comparator 225. The comparator 225 compares the reference triangular wave and the output of the error amplifier 223 to form a PWM signal. The PWM signal formed in the comparator 225 is alternately distributed to the two output terminals in the distributor 226 to drive each of the first switching element 207 to the fourth switching element 210.

The operation of the conventional switching power supply device configured as described above will be described with reference to the operation waveform diagram of FIG.
In FIG. 5, a waveform A in (a) is an output signal waveform from the error amplifier 223, and a waveform B in (a) is an output signal waveform from the triangular wave generation circuit 224. FIG. 5B shows the output signal waveform of the comparator 225. 5C shows driving waveforms of the first switching element 207 and the third switching element 209, and FIG. 5D shows driving waveforms of the second switching element 209 and the fourth switching element 210. Show. FIG. 5E shows an applied voltage waveform of the first switching element 207, and FIG. 5F shows an applied voltage waveform of the second switching element 208. (G) of FIG. 5 shows the applied voltage waveform of the primary winding 211a of the first transformer 211 and the primary winding 212a of the second transformer 212, and (h) shows the first choke coil 215 and The current waveform of the second choke coil 219 is shown.

As shown in FIGS. 5C and 5D, the first switching element 207 and the second switching element 208 operate with a phase difference of 180 degrees from each other by the drive signal from the distributor 226, and are almost the same. The on / off operation is performed so that the duty ratio is not turned on at the same time.
When the first switching element 207 is on, the voltage of the first capacitor 203 is applied to the primary winding 211a of the first transformer 211, and when the second switching element 208 is on, the second The voltage of the capacitor 204 is applied to the primary winding 211 a of the first transformer 211. In addition, when the first switching element 207 is in an on state, a voltage obtained by adding the voltage of the first capacitor 203 and the voltage of the second capacitor 204 is applied to the second switching element 208 ((( f)), when the second switching element 208 is in the ON state, a voltage obtained by adding the voltage of the first capacitor 203 and the voltage of the second capacitor 204 is applied to the first switching element 207 (see FIG. (See (e) of FIG. 5).

When both the first switching element 207 and the second switching element 208 are off, the voltage of the first capacitor 203 and the voltage of the second capacitor 204 are applied to each.
The transition of the applied voltage in the on / off operation of the third switching element 209 and the fourth switching element 210 is the same as the transition of the applied voltage in the on / off operation of the first switching element 207 and the second switching element 208 described above. is there.

If the duty ratios of the first switching element 207 to the fourth switching element 210 are substantially the same, the applied voltages of the first capacitor 203 to the fourth capacitor 206 are substantially the same, and each of the input DC voltages 1/4. Therefore, only half the input DC voltage is applied to each switching element 207, 208, 209, 210. Further, only 1/4 of the input DC voltage is applied to the primary windings 211a and 212a of the transformers 211 and 212, respectively.
The voltages generated in the secondary windings 211b and 211c of the first transformer 211 and the secondary windings 212b and 212c of the second transformer 212 are rectified by the first to fourth rectifier diodes 213, 214, 217, and 218. And smoothed by the first choke coil 215, the second choke coil 219, and the smoothing capacitor 216.

Only during the ON period of the first to fourth switching elements 207, 208, 209, 210, the secondary windings 211b, 211c of the first transformer 211 and the secondary windings 212b, 212c of the second transformer 212 are ( A voltage represented by ¼) · (Ns / Np) · Vin is generated. Here, Np is the number of turns of the primary winding 211a of the first transformer 211 and the primary winding 212a of the second transformer 212, and Ns is the number of turns of the secondary windings 211b and 211c of the first transformer 211. 2 is the number of turns of the secondary windings 212b and 212c of the transformer 212. Vin represents an input DC voltage value. Therefore, the on-period of the first to fourth switching elements 207, 208, 209, and 210 is adjusted to change the product of the voltage and time applied to the first choke coil 215 and the second choke coil 219. As a result, the smoothed output voltage value can be adjusted.

The output voltage is compared with the reference voltage of the reference power supply 222 in the error amplifier 223, the error is amplified, compared with the reference triangular wave in the comparator 225, and fed back to the PWM signal. As described above, in the conventional switching power supply device shown in FIG. 4, the output voltage is fed back to stabilize the output.
In the conventional switching power supply apparatus using the input side DC connection method as described above, the voltage applied to the switching element is half of the input voltage, and the voltage applied to the primary winding of the transformer is the input voltage. Since it is 1/4, the applied voltage of the switching element and the applied voltage of the primary winding of the transformer in the half-bridge converter can be reduced to about half. As a result, in the conventional switching power supply device, it is possible to use a switching element having a low withstand voltage and to reduce the number of windings of the transformer.

Next, current mode control used as a control method in the conventional switching power supply apparatus will be described.
FIG. 6 is a circuit diagram showing a case where current mode control is applied to a switching power supply device for a step-down converter. In FIG. 6, an input DC voltage from an input DC power supply 201 is supplied to input terminals 202a and 202b, and a capacitor 227 is connected between the input terminals 202a and 202b. A series body of a first switching element 228 and a second switching element 229 is connected to the capacitor 227, and the first switching element 228 and the second switching element 229 are configured to alternately repeat on / off operations. Yes.
As shown in FIG. 6, one end of the choke coil 230 is connected to the connection point of the first switching element 228 and the second switching element 229, and the smoothing capacitor 231 is connected to the other end of the choke coil 230. ing. The choke coil 230 and the smoothing capacitor 231 are connected in series, and both ends of the smoothing capacitor 231 are connected to the output terminals 232a and 232b. Electric power is supplied to the load 233 connected to the output terminals 232a and 232b.

  In the conventional switching power supply device configured as described above, when the first switching element 228 is in the ON state, the input voltage is applied to the series circuit of the choke coil 230 and the smoothing capacitor 231. When the second switching element 229 is on, the series circuit of the choke coil 230 and the smoothing capacitor 231 is short-circuited.

  As shown in FIG. 6, the voltage generated at the positive output terminal 232 a is input to one of the first error amplifiers 235, and the reference voltage from the reference power supply 234 is input to the other of the first error amplifiers 235. The The first error amplifier 235 compares the output voltage of the output terminals 232a and 232b with the reference voltage of the reference power source 234, amplifies the error, and outputs the amplified error to the second error amplifier 237. The current detector 236 detects the current flowing through the choke coil 230 and outputs it to the second error amplifier 237. The second error amplifier 237 compares the output of the first error amplifier 235 and the output of the current detector 236, amplifies the error, and outputs the amplified error to the comparator 239. In the comparator 239, the reference triangular wave from the triangular wave generator 238 is compared with the output of the second error amplifier 237 to form a PWM signal. The ON period of the first switching element 228 is determined by this PWM signal, and the first switching element 228 is driven. The inverter 240 inverts the PWM signal from the comparator 239 and drives the second switching element 229.

Next, the operation of the conventional switching power supply having the configuration shown in FIG. 6 will be described.
When the state averaging method is used, when the input voltage Vin is applied to the series circuit of the choke coil 230 and the smoothing capacitor 231 by the duty ratio D by the series circuit of the first switching element 228 and the second switching element 229. Therefore, the following equation (1) to (3) is established. Here, v _out indicates an output voltage, and i _L indicates an output current (choke coil current). The Laplace transform between the output current i _L and the output voltage v _out is defined as I and V.

  In addition, I is shown by Formula (4) and V is shown by Formula (5).

  As shown in Expression (5), the output voltage becomes a second-order lag and the phase is delayed by a maximum of 180 degrees. However, as shown in Equation (4), the choke coil current that is the output current has a slight phase lag at the resonance point, but has a phase lag of approximately 90 degrees because the numerator is first order. Therefore, it can be seen that the PWM control of the choke coil current is significantly more stable than the PWM control of the output voltage. In the current mode control in the conventional switching power supply device shown in FIG. 6, the current control of the choke coil 230 is performed by PWM, and an error signal between the output voltage and the reference voltage is amplified and used as a reference signal used at that time. . The relationship between the choke coil current and the output voltage is expressed by the following equation (6).

The current control loop in the current mode control configured as described above has the characteristics that the phase delay is small and stable, and the gain can be set large. Since this current control loop basically constitutes a first-order lag system, it has a feature that an oscillation phenomenon due to a phase lag does not occur even if the bandwidth is increased. By configuring in this way with current mode control, the transfer characteristic from the reference signal to the choke coil current as the output current becomes almost no delay. For this reason, the loop gain of the voltage control system can construct a stable control system by general PI control.
JP 62-138061 A (page 2-3, FIG. 1)

As described above, in the conventional switching power supply device, it is possible to use a switching element having a low withstand voltage and to reduce the number of windings of the transformer in the input side series connection system of a plurality of switching power supply circuits. However, the conventional switching power supply device has a problem in terms of output voltage stability. On the other hand, the current mode control method has a problem that the output is stable, but a switching element having a withstand voltage corresponding to the input voltage must be used.
However, in the field of switching power supply devices, with the demand for high output voltage stability, there are increasing demands for simultaneously implementing the input-side series connection method and the current mode control method for a plurality of switching power supply circuits. If you try to implement a series connection of multiple switching power supply circuits and current mode control at the same time, the current value of each switching power supply circuit that is a converter corresponds to the current reference value using an error signal between the output voltage and the reference voltage. You have to control it. Here, a change in current balance between the converters when a difference occurs in the duty ratio of the converters will be considered. That is, the two converters connected in series on the input side are A and B, and the duty ratios are Da and Db. The current that flows when the switching elements of the converters A and B are in the ON state is determined by the current that flows through the choke coils of the converters A and B, and the currents (primary currents) that flow through the switching elements are Isa and Isb. And Since the two converters A and B are connected in series, the following expression (7) is established in the stable state.

  Therefore, when the duty ratio of one converter becomes relatively large with respect to the duty ratio of the other converter, the primary current of one converter becomes small, so that equilibrium is maintained. That is, when the duty ratio increases, the primary current of the converter decreases. When this operation is viewed from the whole converter, in order to increase the output current, the duty ratio must be increased, resulting in a contradiction. As a result, since individual current control becomes positive feedback, it becomes impossible to balance. And the balance of the voltage when a plurality of converters are connected in series is lost, and a serious problem arises that an excessive voltage is applied to one converter.

Therefore, in the conventional switching power supply device, there is a problem that when the current mode control method is applied to the input side series connection method of a plurality of switching power supply circuits, the current voltage between the converters cannot be balanced. The problem of simultaneously executing the input side series connection method and the current mode control method of the switching power supply circuit in one device could not be achieved.
The present invention achieves the problem of simultaneously implementing an input side series connection method and a current mode control method of a switching power supply circuit in one device, and even if a plurality of switching power supply circuits are connected in series, An object of the present invention is to provide a highly stable, small, and highly efficient switching power supply device that can maintain a good current balance without impairing mode control characteristics.

In order to achieve the above object, a switching power supply device according to the present invention includes:
A plurality of converters, in which the input side is connected in series and the output side is connected in parallel, each of which is constituted by a plurality of switching means, a transforming means, and a rectifying means to output a single output DC voltage;
A first error amplifier that compares the single output DC voltage output from the converter with a reference voltage to form a first error signal and outputs a current reference signal obtained by amplifying the first error signal ;
An arithmetic unit that adds the currents output from the rectifiers in the plurality of converters to form a single output current signal;
A second error amplifier that compares the single output current signal of the computing unit with the current reference signal output from the first error amplifier to form and amplify a second error signal; and the PWM signal is formed based on the output signal of the error amplifier, said plurality of converters to not controlled individually on the basis of the current output from the rectifying means, said current reference signal to each of said plurality of switching means A plurality of PWM signal generators that perform PWM control using the PWM signal corresponding to The switching power supply device of the present invention configured as described above is highly stable and can maintain a good current balance without impairing the characteristics of current mode control even when a plurality of converters are connected in series on the input side. Thus, a small and highly efficient power supply device can be provided.

The control method of the switching power supply device according to the present invention includes:
In a switching power supply apparatus having a plurality of converters, each having an input side connected in series and an output side connected in parallel, each of which is constituted by a plurality of switching means, a transformer means, and a rectifier means to output a single output DC voltage.
Comparing the single output DC voltage with a reference voltage to form a first error signal, and outputting a current reference signal obtained by amplifying the first error signal ;
Adding the current output from the rectifiers in the plurality of converters to form a single output current signal;
Comparing the single output current signal with the current reference signal to form and amplify a second error signal;
Based on the second error signal amplified to form a PWM signal, a plurality of converters to not controlled individually on the basis of the current output from the rectifying means, said current each of said plurality of switching means And PWM control using the PWM signal corresponding to the reference signal . The control method of the switching power supply apparatus of the present invention having such steps is highly stable and has a good current balance without impairing the characteristics of the current mode control even when a plurality of converters are connected in series on the input side. Can keep.
In addition, a switching power supply device according to another aspect of the present invention includes:
A plurality of converters, in which the input side is connected in series and the output side is connected in parallel, each of which is constituted by a plurality of switching means, a transforming means, and a rectifying means to output a single output DC voltage;
A first error amplifier that compares the single output DC voltage output from the converter with a reference voltage to form a first error signal and outputs a current reference signal obtained by amplifying the first error signal ;
A current signal output from the rectifying means in any one of the plurality of converters is compared with the current reference signal output from the first error amplifier to form a second error signal and amplified A second error amplifier, and
A PWM signal is formed on the basis of an output signal of the second error amplifier, and each of the plurality of switching means is controlled so as not to individually control the plurality of converters based on currents output from the respective rectifying means. A plurality of PWM signal generators that perform PWM control using the PWM signal corresponding to the current reference signal;
The novel features of the invention are nonetheless specifically set forth in the appended claims, but the invention, both in terms of structure and content, should be read in conjunction with the drawings and in the detailed description that follows. Will be better understood and appreciated.

In the present invention, the problem of simultaneously performing the input side series connection method and the current mode control method of the switching power supply circuit in one device is achieved, and even if a plurality of switching power supply circuits are connected in series, It is possible to provide a highly stable, small and highly efficient switching power supply device and a control method thereof that can maintain a good current balance without impairing the characteristics of current mode control.
The switching power supply device of the present invention is stable without unstable operation even when the input side of a plurality of switching power supply circuits is connected in series and the output side is connected in parallel and current mode control is performed by the control unit. Excellent control is possible.
The switching power supply control method of the present invention has an excellent effect that even if a plurality of converters are connected in series, the current mode control characteristics are not impaired, and the current balance can be kept high and stable. Play.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment showing a switching power supply device and a control method thereof according to the invention will be described with reference to the accompanying drawings.

Embodiment 1
FIG. 1 is a circuit diagram showing a configuration of a switching power supply according to Embodiment 1 of the present invention. In FIG. 1, an input DC voltage from an input DC power source 1 is supplied to input terminals 2a and 2b, and a series circuit of a plurality of capacitors 3, 4, 5, and 6 is connected to the input terminals 2a and 2b. The input DC voltage applied to the input terminals 2a and 2b is divided by the capacitors 3, 4, 5, and 6, respectively. In the following description, each of a plurality of capacitors 3, 4, 5, 6 connected to the input terminals 2a, 2b is replaced with a first capacitor 3, a second capacitor 4, a third capacitor 5, and a fourth capacitor. It is called 6. A series circuit of the first switching element 7 and the second switching element 8 is connected to both ends of the series circuit of the first capacitor 3 and the second capacitor 4, and the third capacitor 5 and the fourth capacitor 6 are connected to each other. A series circuit of a third switching element 9 and a fourth switching element 10 is connected to both ends of the series circuit.

The first transformer 11 has a primary winding 11a, a first secondary winding 11b, and a second secondary winding 11c. One end of the primary winding 11 a is connected to a connection point between the first capacitor 3 and the second capacitor 4, and the other end of the primary winding 11 a is the first switching element 7 and the second switching element 8. Connected to the connection point. The first secondary winding 11b and the second secondary winding 11c are connected in series.
The second transformer 12 has a primary winding 12a, a first secondary winding 12b, and a second secondary winding 12c. One end of the primary winding 12 a is connected to the connection point of the third capacitor 5 and the fourth capacitor 6, and the other end of the primary winding 12 a is the third switching element 9 and the fourth switching element 10. Connected to the connection point. The first secondary winding 12b and the second secondary winding 12c are connected in series.

The anode of the first rectifier diode 13 is connected to the first secondary winding 11b of the first transformer 11, and the anode of the second rectifier diode 14 is connected to the second secondary winding 11c. Has been. The cathodes of the first rectifier diode 13 and the second rectifier diode 14 are connected to each other. In this way, the first rectifier diode 13 and the second rectifier diode 14 are connected to the first transformer 11, and the alternating current generated in the first secondary winding 11b and the second secondary winding 11c. The current is rectified.
As shown in FIG. 1, one end of the series circuit of the first choke coil 15 and the smoothing capacitor 16 is connected to a connection point between the first secondary winding 11b and the second secondary winding 11c. The other end of the series circuit is connected to a connection point (cathode) between the first rectifier diode 13 and the second rectifier diode 14.

The anode of the third rectifier diode 17 is connected to the first secondary winding 12b of the second transformer 12, and the anode of the fourth rectifier diode 18 is connected to the second secondary winding 12c. Has been. The cathodes of the third rectifier diode 17 and the fourth rectifier diode 18 are connected to each other. In this way, the third rectifier diode 17 and the fourth rectifier diode 18 are connected to the second transformer 12, and the AC generated in the first secondary winding 12b and the second secondary winding 12c. The current is rectified.
One end of the second choke coil 19 is connected to the connection point (cathode) of the third rectifier diode 17 and the fourth rectifier diode 18, and the other end is connected to one end of the smoothing capacitor 16. Both ends of the smoothing capacitor 16 are connected to the output terminals 20a and 20b, and power is supplied to the load 21 connected to the output terminals 20a and 20b.

As shown in FIG. 1, the voltage generated at the positive output terminal 20 a is input to one of the first error amplifiers 23, and the reference voltage from the reference power supply 22 is input to the other of the first error amplifiers 23. The The first error amplifier 23 compares the output voltage of the output terminals 20a and 20b with the reference voltage of the reference power supply 22, and amplifies the error.
The first current detector 24 detects a current flowing through the first choke coil 15, and the second current detector 25 detects a current flowing through the second choke coil 19. An adder 26 which is an arithmetic unit adds the output of the first current detector 24 and the output of the second current detector 25 to form a single current signal and outputs the single current signal to the second error amplifier 27. . The second error amplifier 27 compares the output of the first error amplifier 23 and the output of the adder 26 and amplifies the error.

The first triangular wave generator 28 generates a first reference triangular wave signal that serves as a reference for forming a first PWM signal to be supplied to each of the first switching element 7 and the second switching element 8. The first reference triangular wave signal from the first triangular wave generator 28 is supplied to one input terminal of the first comparator 30. The first comparator 30 compares the first reference triangular wave signal and the output signal from the second error amplifier 27 to form a first PWM signal. The first PWM signal formed in the first comparator 30 is alternately distributed to the two output terminals in the first distributor 31, and the first switching element 7 and the second switching element 8 are respectively transmitted. To drive.

  The second triangular wave generator 29 generates a second reference triangular wave signal serving as a reference for forming a second PWM signal supplied to each of the third switching element 9 and the fourth switching element 10. The second reference triangular wave signal from the second triangular wave generator 29 is supplied to one input terminal of the second comparator 32. The second comparator 32 compares the second reference triangular wave signal with the output signal from the second error amplifier 27 to form a second PWM signal. The second PWM signal formed in the second comparator 32 is alternately distributed to the two output terminals in the second distributor 33, and each of the third switching element 9 and the fourth switching element 10 is distributed. To drive.

In the switching power supply device of the first embodiment, the first capacitor 3, the second capacitor 4, the first switching element 7, the second switching element 8, the first transformer 11, the first rectifier diode 13, the first capacitor Two rectifier diodes 14, a first choke coil 15, and a smoothing capacitor 16 constitute a first half-bridge converter 100.
In the switching power supply device of the first embodiment, the third capacitor 5, the fourth capacitor 6, the third switching element 9, the fourth switching element 10, the second transformer 12, and the third rectifier diode 17, the fourth rectifier diode 18, the second choke coil 19, and the smoothing capacitor 16 constitute a second half-bridge converter 101. In the switching power supply device of the first embodiment shown in FIG. 1, the smoothing capacitor 16 is shared by the first half-bridge converter 100 and the second half-bridge converter 101.

  In the switching power supply according to the first embodiment, the first half-bridge converter 100 and the second half-bridge converter 101 are driven and controlled by the control unit, and the control unit includes the first error amplifier 23 and the first current. The detector 24, the second current detector 25, the adder 26, the second error amplifier 27, the first PWM signal generator 103, and the second PWM signal generator 104 are configured. Here, the first PWM signal generator 103 includes a first triangular wave generator 28, a first comparator 30, and a first distributor 31, and the second PWM signal generator 104 is a second PWM signal generator 104. The triangular wave generator 29, the second comparator 32, and the second distributor 33.

The operation of the switching power supply device according to the first embodiment configured as described above will be described with reference to FIG. FIG. 2 is a signal waveform diagram of each part in the switching power supply device of the first embodiment.
In FIG. 2, a waveform A in (a) is an output signal waveform from the second error amplifier 27, and a waveform B in (a) is an output signal waveform from the second triangular wave oscillator 29. A waveform C in FIG. 2B is an output signal waveform from the second error amplifier 27, and a waveform D in FIG. 2B is an output signal waveform of the first triangular wave oscillator 28. FIG. 2C shows the drive waveform of the first switching element 7, and FIG. 2D shows the drive waveform of the second switching element 8. FIG. 2E shows the drive waveform of the third switching element 9, and FIG. 2F shows the drive waveform of the fourth switching element 10. FIG. 2G shows the applied voltage waveform of the primary winding 11a of the first transformer 11, and FIG. 2H shows the applied voltage waveform of the primary winding 12a of the second transformer 12. . 2 (i) shows the current waveform of the first choke coil 15, and (j) shows the current waveform of the second choke coil 19. FIG. FIG. 2K shows the voltage waveform output from the adder 26.

In FIG. 2, when the first switching element 7 is turned on at time T <b> 0, the voltage held by the first capacitor 3 is applied to the primary winding 11 a of the first transformer 11. At this time, a voltage corresponding to the turn ratio is generated in the first secondary winding 11b of the first transformer 11, and the first rectifier diode 13 is turned on. For this reason, a voltage is applied to the first choke coil 15 and the current of the first choke coil 15 increases.
When the first switching element 7 is turned off at time T3, the primary winding 11a of the first transformer 11 is opened and the current becomes zero. Thereby, since the current of the first choke coil 15 is divided and flows through the first secondary winding 11b and the second secondary winding 11c of the first transformer 11, the first rectifier diode 13 And the second rectifier diode 14 is turned on, and the voltages generated in the primary winding 11a, the first secondary winding 11b, and the second secondary winding 11c of the first transformer 11 become zero. Therefore, the voltage applied to the series circuit of the first choke coil 15 and the smoothing capacitor 16 becomes 0 V, so the voltage of the first choke coil 15 decreases.

When the second switching element 8 is turned on at time T4, the voltage of the second capacitor 4 is applied to the primary winding 11a of the first transformer 11. The voltage at this time is a voltage opposite to that at the time T0 to T3. Accordingly, reverse voltages are also generated in the first secondary winding 11b and the second secondary winding 11c of the transformer 11, and the first rectifier diode 13 is turned off. At this time, a voltage corresponding to the turn ratio of the first transformer 11 is induced in the first choke coil 15 via the second rectifier diode 14 in the on state, and the current flowing through the first choke coil 15 is To increase.
When the second switching element 8 is turned off at time T7, the primary winding 11a of the first transformer 11 is opened, and the current becomes zero. Since the current of the first choke coil 15 flows by dividing the first secondary winding 11b and the second secondary winding 11c of the first transformer 11, the first rectifier diode 13 and the second rectifier The diode 14 is turned on. At this time, the voltage applied to all the windings of the first transformer 11 becomes zero. At this time, since 0 V is applied to the series circuit of the first choke coil 15 and the smoothing capacitor 16, the current of the first choke coil 15 decreases.

  As described above, the first half-bridge converter 100 of the switching power supply apparatus according to the first embodiment operates, and the same operation is performed by the third capacitor 5, the fourth capacitor 6, and the third switching element 9. In the second half-bridge converter 101 composed of the fourth switching element 10, the second transformer 12, the third rectifier diode 17, the fourth rectifier diode 18, the second choke coil 19, and the smoothing capacitor 16. Done. Therefore, detailed operation description of the second half-bridge converter 101 is omitted. However, the first half-bridge converter 100 and the second half-bridge converter 101 operate synchronously, and further, the reference signals from the first triangular wave oscillator 28 and the second triangular wave oscillator 29, which are reference signals in the first half bridge converter 100 and the second half bridge converter 101, respectively. The triangular wave signals have a phase difference of 180 degrees from each other. Therefore, the first choke coil operates with a phase difference of 180 degrees on the secondary side of the first half-bridge converter 100 and the second half-bridge converter 101 of the switching power supply according to the first embodiment. Since the current flowing through 15 and the current flowing through the second choke coil 19 are added and output, the ripples generated in each of them are canceled out and become smaller.

  Next, the control unit of the switching power supply device according to the first embodiment will be described. The control unit is a part that drives and controls the first half-bridge converter 100 and the second half-bridge converter 101, and includes a first error amplifier 23, a first current detector 24, a second current detector 25, The adder 26, the second error amplifier 27, the first PWM signal generator 103, and the second PWM signal generator 104 are configured.

  In the switching power supply device of the first embodiment, the current flowing through the first choke coil 15 and the current flowing through the second choke coil 19 are added and smoothed by the smoothing capacitor 16 to become a single output current. is there. In the first embodiment, the current detected by the first current detector 24 by the adder 26 and the current detected by the second current detector 25 are added. Therefore, the output of the adder 26 indicates the charging current of the smoothing capacitor 16. In the first error amplifier 23, the output voltage of the output terminals 20a and 20b and the reference voltage of the reference power source 22 are compared, and the error is amplified and used as a current reference signal. The current reference signal and the output signal from the adder 26 are compared in the second error amplifier 27, the error is amplified, and PWM control is performed so that the difference is reduced. A reference triangular wave signal that is a reference for PWM control is output from the first triangular wave generator 30 and the second triangular wave generator 32 with a phase difference of 180 degrees from each other, and the on / off timing of each switching element is changed. It is set to cancel the ripple current at the output end.

The first PWM signal obtained by comparing the output of the first triangular wave oscillator 28 and the output of the second error amplifier 27 is distributed into two by the first distributor 31. The first distributor 31 drives the first switching element 7 and the second switching element 8 by the distributed first PWM signal. As described above, the first switching element 7 and the second switching element 8 are configured to distribute and drive the first PWM signal by the first distributor 31. The two switching elements 8 are not simultaneously turned on.
Similarly, the second PWM signal obtained by comparing the output of the second triangular wave oscillator 29 and the output of the second error amplifier 27 is distributed into two by the second distributor 33. The second distributor 33 drives the third switching element 9 and the fourth switching element 10 by the distributed second PWM signal. Thus, since the 3rd switching element 9 and the 4th switching element 10 are the structures which distribute and drive the 2nd PWM signal by the 2nd divider | distributor 33, they are the 3rd switching element 9 and the 3rd switching element. The four switching elements 10 are not simultaneously turned on.

  As described above, in the switching power supply device of the first embodiment, the sum of the output currents of the first half-bridge converter 100 and the second half-bridge converter 101 is controlled to correspond to the current reference signal. It is a configuration. For this reason, the switching power supply according to the first embodiment is not configured to individually control each of the first half-bridge converter 100 and the second half-bridge converter 101 according to the current reference signal. Therefore, in the conventional switching power supply apparatus described in the above-mentioned prior art section, when each of the converters is individually controlled, the current changes accordingly when the duty ratio changes, for example, the duty ratio increases (decreases). ) Does not occur in the switching power supply device of the first embodiment. For this reason, the switching power supply according to the first embodiment always forms a stable output current, and the output current can be controlled.

  In the switching power supply device of the first embodiment, the outputs of the first current detector 24 and the second current detector 25 are added by the adder 26, and the addition result is supplied to the second error amplifier 27. It is an input configuration. However, the adder used in the present invention does not need to be an adder circuit in a strict sense, and has an offset necessary for securing the operating point of the adder 26 and the second error amplifier 27. Also good. Even if such a device is used, the switching control operation in the switching power supply device is not affected. Even if a non-linear arithmetic unit that is a function of monotonic increase or monotonous decrease is used in place of the adder, the current is not individually controlled for each converter, so that the output does not become unstable. The effect is kept. The monotonically increasing function and the monotonically decreasing function y = f (x1, x2) are expressed by the following inequality (8).

  In particular, when a symmetric function is used with respect to each input of an adder, an integrator, etc., the phase difference of the ripple of the current signal that differs depending on each converter can be eliminated, and the operation becomes more stable. For example, when the output (x1, x2) from the two converters is input to the arithmetic unit in the switching power supply device constituted by the two converters, if the output of the arithmetic unit is expressed by Expression (9), The computing unit in the invention has the condition shown by the equation (10).

That is, the arithmetic unit in the present invention satisfies the condition that the outputs of the arithmetic units are the same even if the outputs (x1, x2) from the two converters are switched and input to the arithmetic unit.
In particular, stable operation is possible even when one of the two converters is used.
Similarly, as shown in the second embodiment, when there are three or more inputs to the computing unit, each condition is a condition that the output is the same when the combination of input values is the same, and all the inputs are On the other hand, it is a condition that monotonously increases or monotonously decreases. In particular, by using an adder, there is a feature that the gain of the arithmetic unit does not change depending on the current value, and the control circuit can be easily adjusted.

  In the first embodiment, an example using an adder or an arithmetic unit has been described. However, a configuration in which the output of one of the two converters is directly input to the second error amplifier 27 without using them. That is, the detection signal of either the first current detector 24 or the second current detector 25 may be input to the second error amplifier 27.

As described above, in the first embodiment, the half-bridge converter is described as an example of the converter. However, the present invention is not limited to such a configuration, and is represented by other forward type, bridge type, and push-pull type. Even when the input side (primary side) is connected in series and the output side (secondary side) is connected in parallel using a switching converter, a similar control system configuration is possible and stable operation is possible. . In particular, when a half bridge converter is used as the converter, in addition to the reduction of the primary winding of the transformer by the input side series connection method, the voltage applied to the primary winding of the transformer becomes small in the half bridge converter. Therefore, it is particularly effective for reducing the size of the transformer.

  As described above, the switching power supply device of the present invention can realize high stability of current mode control in addition to the effect of reducing the voltage applied to the switching element by the serial connection on the input side. In particular, in a power supply for supplying power to a semiconductor device such as a microprocessor, a large current (e.g., 1 V) from a relatively high bus voltage (e.g., 48 V) that distributes power to each part of the device is used. For example, it is necessary to convert to 100A). The switching power supply device of the present invention has a configuration that can be converted in this way. The switching power supply device of the present invention can cope with a high bus voltage by connecting input circuits in series, and can achieve high stability by current mode control. It is effective as a device.

<< Embodiment 2 >>
FIG. 3 is a circuit diagram showing a configuration of the switching power supply according to Embodiment 2 of the present invention. The switching power supply according to the second embodiment differs from the switching power supply according to the first embodiment in the number of configurations of the half bridge converter used as a converter. In the first embodiment, it is constituted by two half-bridge converters, and in the second embodiment, it is constituted by three half-bridge converters. The operation of each converter is the same as the operation described in the first embodiment and is omitted because it is duplicated.

In FIG. 3, the input DC voltage from the input DC power source 1 is supplied to the input terminals 2a and 2b. The input terminals 2a and 2b have a first half-bridge converter 300, a second half-bridge converter 303, and Each input side of the third half-bridge converter 306 is connected in series. Each of the first to third half-bridge converters 300, 303, and 306 includes a capacitor, a switching element, a transformer, a rectifier diode, a choke coil, and a current, as in the half-bridge converters 100 and 101 in the first embodiment. A detector and a smoothing capacitor are provided.
The smoothing capacitor 16 adds the output currents of the first half-bridge converter 300, the second half-bridge converter 303, and the third half-bridge converter 306, and then smoothes and absorbs the ripple current. Both ends of the smoothing capacitor 16 are connected to the output terminals 20a and 20b, and power is supplied to the load 21 connected to the output terminals 20a and 20b.

As shown in FIG. 3, the voltage generated at the positive output terminal 20 a is input to one of the first error amplifiers 23, and the reference voltage from the reference power supply 22 is input to the other of the first error amplifiers 23. The The first error amplifier 23 compares the output voltage of the output terminals 20a and 20b with the reference voltage of the reference power supply 22, and amplifies the error.
The first current detector 302 detects the current flowing through the first choke coil 301, the second current detector 305 detects the current flowing through the second choke coil 304, and the third current detector 308 The current flowing through the third choke coil 307 is detected. An adder 309, which is an arithmetic unit, adds the outputs of the first current detector 302, the second current detector 305, and the third current detector 308 to form a single current signal. Output to the error amplifier 27. The second error amplifier 27 compares the output of the first error amplifier 23 with the output of the adder 309 and amplifies the error.

  The first reference triangular wave signal from the first triangular wave generator 310 is supplied to one input terminal of the first comparator 313. The first comparator 313 compares the first reference triangular wave signal and the output signal from the second error amplifier 27 to form a first PWM signal. The first PWM signal formed in the first comparator 313 is alternately distributed to the two output terminals in the first distributor 314, and the two switching elements VG1 and VG2 of the first half-bridge converter 300 are distributed. Drive each one.

  The second reference triangular wave signal from the second triangular wave generator 311 is supplied to one input terminal of the second comparator 315. The second comparator 315 compares the second reference triangular wave signal and the output signal from the second error amplifier 27 to form a second PWM signal. The second PWM signal formed in the second comparator 315 is alternately distributed to the two output terminals in the second distributor 316, and the two switching elements VG3 and VG4 of the second half-bridge converter 303 are supplied. Drive each one.

The third reference triangular wave signal from the third triangular wave generator 312 is supplied to one input terminal of the third comparator 317. The third comparator 317 compares the third reference triangular wave signal and the output signal from the second error amplifier 27 to form a third PWM signal. The third PWM signal formed in the third comparator 317 is alternately distributed to the two output terminals in the third distributor 318, and the two switching elements VG5 and VG6 of the third half-bridge converter 306 are output. Drive each one.
The first to third reference triangular wave signals output from the first to third triangular wave oscillators 310, 311, and 312 have a phase difference of 120 degrees from each other, and the first to third half-bridge converters 300, The ripple current is canceled out at the output ends of 303 and 306 and is reduced.

The operation of the switching power supply according to Embodiment 2 configured as described above will be described.
The operation of the switching power supply device according to the second embodiment is different from the first embodiment described above in that the number of half-bridge converters is three. The output currents of the first to third half-bridge converters 300, 303, and 306 operate in three phases that are 120 degrees out of phase, and the output currents are added to cancel the ripple currents. .
In the switching power supply device of the second embodiment, the input voltage to each half-bridge converter is further reduced, and the voltage applied to each switching element is 1/3 of the input voltage, that is, (1/3) Vin, The voltage applied to the primary winding of the transformer is 1/6 of the input voltage, that is, (1/6) Vin. Therefore, the configuration of the second embodiment is advantageous for improving the efficiency of the switching power supply device and reducing the size of the transformer. Furthermore, since the switching power supply device of the second embodiment operates at a frequency that is three times that of the single operation, the output ripple can be stabilized with a small number of smoothing capacitors.

  The control unit of the switching power supply apparatus according to the second embodiment is a part that controls driving of the first to third half-bridge converters 300, 303, and 306, and includes a first error amplifier 23, a second error amplifier 27, and a second error amplifier. 1st to 3rd current detectors 302, 305, 308, adder 309, 1st to 3rd triangular wave oscillators 310, 311, 312, 1st to 3rd comparators 313, 315, 317, and 1st to 3rd 3 distributors 314, 316, and 318.

  In the control unit, the outputs of the first to third current detectors 302, 305, and 308 in the first to third half-bridge converters 300, 303, and 305 are all added by the adder 309, and the second error is added. It is input to the amplifier 27. The second error amplifier 27 receives the current reference signal obtained by the first error amplifier 23, and is controlled so that the sum of the output currents corresponds to the current reference signal. Therefore, the switching power supply device according to the second embodiment is not configured to individually control the output current of each half-bridge converter, so that there is no instability factor and the operation is stable.

In the switching power supply device according to the second embodiment, the outputs of the first current detector 302, the second current detector 305, and the third current detector 308 are added by the adder 309, and the second error amplifier is added. 27. However, the adder used in the present invention is not necessarily an adder circuit in a strict sense, and has an offset necessary for securing the operating point of the adder 309 and the second error amplifier 27. Also good. Even if such a device is used, the switching control operation in the switching power supply device of the second embodiment is not affected.
Even if a nonlinear arithmetic unit that is a function of a monotonous increase or monotonic decrease that is symmetric with respect to each input of an accumulator or the like is used instead of an adder, it is not configured to individually control each converter current. Therefore, the effect of the present invention that the output does not become unstable is maintained. In particular, when an adder is used, the charging current of the smoothing capacitor is proportional to the addition result that is the output of the adder. Therefore, in addition to the stable operation, the output voltage becomes a first-order lag with respect to the added current, and the phase The advantage of the current mode control that the delay is reduced can be maintained.

In the switching power supply device according to the second embodiment, three converters have been described as an example. Even when four or more converters are used, the currents of the respective converters are detected and added to obtain a sum. It goes without saying that the same effect as in the second embodiment can be obtained by configuring the control so as to control the above.
In the second embodiment, an example using an adder has been described. However, a configuration in which the output of any of the three converters is directly input to the second error amplifier 27 without using an adder, that is, The detection signal of any of the first current detector 302, the second current detector 305, and the third current detector 308 may be input to the second error amplifier 27.
In the second embodiment, the half bridge converter has been described as an example. However, the same effect can be obtained with other forward type converters, bridge type converters, or push-pull type converters.
The switching power supply according to the second embodiment is also particularly effective as a power supply for supplying power to the semiconductor device as described in the first embodiment.

  Although the invention has been described in its preferred form with a certain degree of detail, the present disclosure of this preferred form should vary in the details of construction, and combinations of elements and changes in order may vary in the claimed invention. It can be realized without departing from the scope and spirit.

According to the present invention, an input side series connection method and a current mode control method of a switching power supply circuit are simultaneously performed in one device, and a highly stable, small and highly efficient switching power supply device and a control method thereof are provided. Therefore, the present invention is useful as a device for supplying a stabilized DC voltage for industrial and consumer electronic devices and a control method therefor.

It is a circuit diagram which shows the structure of the switching power supply device of Embodiment 1 which concerns on this invention. It is a wave form diagram which shows the operation | movement in the switching power supply device of Embodiment 1 which concerns on this invention. It is a circuit diagram which shows the structure of the switching power supply apparatus of Embodiment 2 which concerns on this invention. It is a circuit diagram which shows the structure of the conventional switching power supply apparatus. It is a wave form diagram which shows the operation | movement in the conventional switching power supply device shown in FIG. It is a circuit diagram which shows the structure of the conventional switching power supply apparatus.

Explanation of symbols

1 Input DC Power Supply 2a Input Terminal 2b Input Terminal 3 First Capacitor 4 Second Capacitor 5 Third Capacitor 6 Fourth Capacitor 7 First Switching Element 8 Second Switching Element 9 Third Switching Element 10 Third 4 switching element 11 first transformer 12 second transformer 13 first rectifier diode 14 second rectifier diode 15 first choke coil 16 smoothing capacitor 17 third rectifier diode 18 fourth rectifier diode 19 second Choke coil 20a output terminal 20b output terminal 21 load 22 reference voltage 23 first error amplifier 24 first current detector 25 second current detector 26 adder 27 second error amplifier 28 first triangular wave oscillator 29 Second triangular wave oscillator 30 First comparator 31 First minute Vessel 32 second comparator 33 a second distributor 100 first half-bridge converter 101 second half-bridge converter

Claims (11)

A plurality of converters, in which the input side is connected in series and the output side is connected in parallel, each of which is constituted by a plurality of switching means, a transforming means, and a rectifying means to output a single output DC voltage;
A first error amplifier that compares the single output DC voltage output from the converter with a reference voltage to form a first error signal and outputs a current reference signal obtained by amplifying the first error signal ;
An arithmetic unit for detecting a current output from the rectifying means in the plurality of converters to form a single output current signal;
A second error amplifier that compares the single output current signal of the computing unit with the current reference signal output from the first error amplifier to form and amplify a second error signal; and the PWM signal is formed based on the output signal of the error amplifier, said plurality of converters to not controlled individually on the basis of the current output from the rectifying means, said current reference signal to each of said plurality of switching means A plurality of PWM signal generators that perform PWM control by the PWM signal corresponding to
A switching power supply device comprising:   Each of the PWM signal generators includes a triangular wave generator that forms a reference triangular wave, a comparator that compares the reference triangular wave of the triangular wave generator with the output signal of the second error amplifier, and a PWM signal based on the comparison result of the comparator And a distributor for PWM controlling the corresponding switching means.   Each of the Q converters has a plurality of capacitors connected in series between the input terminals, and each of the capacitors is connected to different switching means, and the triangular wave generators of the Q PWM signal generators are mutually π A reference triangular wave having a phase difference of / Q is output, and the PWM signal generator is configured to change the switching timing for each converter using the reference triangular wave and the output signal of the second error amplifier. The switching power supply device according to claim 2.   4. The arithmetic unit includes an adder, and the adder adds currents output from the rectifiers of the plurality of converters to form a single output current signal. 5. The switching power supply device according to item.   The switching power supply according to any one of claims 1 to 4, wherein the converter is a half-bridge converter.   The switching power supply device according to any one of claims 1 to 5, wherein the PWM signal formed in the PWM signal generator is phase-shifted at substantially equal intervals.   The switching power supply device according to claim 1, wherein the switching power supply device is configured to supply power to the semiconductor device. In a switching power supply apparatus having a plurality of converters, each having an input side connected in series and an output side connected in parallel, each of which is constituted by a plurality of switching means, a transformer means, and a rectifier means to output a single output DC voltage.
Comparing the single output DC voltage with a reference voltage to form a first error signal, and outputting a current reference signal obtained by amplifying the first error signal ;
Calculating a current output from the rectifying means in the plurality of converters to form a single output current signal;
Comparing the single output current signal with the current reference signal to form and amplify a second error signal;
Based on the second error signal amplified to form a PWM signal, a plurality of converters to not controlled individually on the basis of the current output from the rectifying means, said current each of said plurality of switching means PWM control by the PWM signal corresponding to the reference signal ;
A control method for a switching power supply device, comprising:   In the step of PWM controlling each of the switching means, the triangular wave generator outputs a reference triangular wave, the comparator compares the reference triangular wave with the amplified second error signal, and the distributor is based on the comparison result of the comparator. 9. The method of controlling a switching power supply device according to claim 8, wherein a PWM signal is formed and the corresponding switching means is subjected to PWM control.   In the switching power supply device in which each of the Q converters has a plurality of capacitors connected in series between the input terminals, and each of the capacitors is connected to different switching means, a triangular wave generator of the Q PWM signal generators 9. The control of the switching power supply device according to claim 8, wherein each outputs a reference triangular wave having a phase difference of π / Q from each other, forms a PWM signal using the reference triangular wave, and changes a switching timing for each converter. Method. A plurality of converters, in which the input side is connected in series and the output side is connected in parallel, each of which is constituted by a plurality of switching means, a transforming means, and a rectifying means to output a single output DC voltage;
A first error amplifier that compares the single output DC voltage output from the converter with a reference voltage to form a first error signal and outputs a current reference signal obtained by amplifying the first error signal ;
A current signal output from the rectifying means in any one of the plurality of converters is compared with the current reference signal output from the first error amplifier to form a second error signal and amplified A second error amplifier that forms a PWM signal based on the output signal of the second error amplifier, and the plurality of converters are not individually controlled based on the current output from each rectifier. A plurality of PWM signal generators for PWM control of each of a plurality of switching means by the PWM signal corresponding to the current reference signal ;
A switching power supply device comprising:

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